1. Field of the Invention
The present invention relates to a vehicle lighting device installed in a vehicle. In particular, the present invention relates to a technique of emitting light forward from a long light guide lens that is obliquely tilted with respect to the front-rear direction.
2. Description of Related Art
Vehicle lighting devices installed in vehicles that emit light from a long light guide lens have been known in the art. In vehicle lighting devices of this type, light enters a light guide lens through a side end face in the longitudinal direction. The incident light is guided in the longitudinal direction, is reflected on lens cuts in the rear face and exits through the front face, so that the light is emitted from the front face of the light guide lens.
However, when the light guide lens of such vehicle lighting devices is disposed extending in an obliquely tilted direction with respect to the front-rear direction of the vehicle lighting device, the light that has entered the light guide lens through a side end face in the longitudinal direction cannot exit forward, i.e. such vehicle lighting devices cannot emit light forward from the front face of the light guide lens.
Specifically, when light is emitted from the front face of a long light guide lens that extends obliquely backward from the right to the left as illustrated in FIG. 6A, light that is emitted from a light source (not shown) opposed to the side end face at the front side in the longitudinal direction is guided in the light guide lens in the obliquely backward direction along the light guide lens. To emit the light forward from the front face of the light guide lens, it is required to internally reflect the light on lens cuts in the rear face at an acute angle. However, when the rear faces of the lens cuts are formed at a steep angle for this purpose, the light escapes backward through the faces. To prevent the light from escaping through the lens cuts, the rear faces of the lens cuts cannot be formed at a very steep angle. As a result, it is impossible to emit the light forward from the light guide lens.
To cope with the problem, a vehicle lighting device described in JP 2011-198537A includes a reflector disposed behind a light guide lens, in which forward light is achieved by reflecting the light that has escaped backward out of the light guide lens on the reflector so that the light re-enters the light guide lens. In more detail, the light that has escaped backward out of the light guide lens is reflected on the reflector at a relatively moderate angle as illustrated in FIG. 6B. Then, the light re-enter the light guide lens through front faces of the lens cuts where the light is refracted, and the incident light is further internally reflected forward on rear faces of the lens cuts.